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(11) | EP 0 125 622 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | X-ray beam filter device |
| (57) A device for linearly oscillating one or more of a plurality of x-ray filter elements
singly or in combination in and out of an x-ray beam at television frame rates. First
and second substantially coplanar filter elements are adjacent each other and formed
as a unitary member that is transverse to the x-ray beam. It is slidable bidirectionally
on parallel guide tracks in one plane. A servo motor drives a closed loop belt which
attaches to said member. A third planar filter element runs on tracks in a plane parallel
to that of the unitary member. There are lug means on the third element spaced apart
in the direction of its travel memberthat project up and are between the lug means
on the third element to enable pushing or pulling it. Thus, the first and second filter
elements can be oscillated alternately in and out of the x-ray beam by moving said
unitary member without engaging the third element so it stays out of the beam. The
member can be driven to one travel limit to pull the third element into the beam and
let it stay there while the first element is oscillated beneath it so the beam passes
through two filters. And the member can be driven to one travel limit and not be oscillated
so the third filter element stays in the beam. |